[The effect of iodination on the biological and immunological activities of the human growth hormone and prolactin].

The human growth hormone (hGH) and human prolactin (hPRL) were iodinated with 125I using the lactoperoxidase method and purified by gel filtration on a Sephadex G-100 column and by ion exchange chromatography on a diethyl-aminoethyl (DEAE) cellulose column. Aliquots of the peak fraction on the Sephadex G-100 column and each fraction on the DEAE cellulose column were tested by radioimmunoassay (RIA) using 131I-hGH or 131I-hPRL as a tracer and by bioassay using Nb2 rat lymphoma cells. The ratio of the bioassay and RIA estimates of 125I-hGH was 0.89 +/- 0.15 (mean +/- SD) and that of both estimates of 125I-hPRL was 1.14 +/- 0.16. These data suggest that the lactoperoxidase iodination method is sufficient for labeling hGH and hPRL to a high specific activity without altering their biological integrity.